import java.util.Scanner;

public class QQQQQQ {
    public static void main(String[] args){
        int a;
        int i=0;
        i+=1;
        Scanner A=new Scanner(System.in);
        a= A.nextInt();
        int[] v={19,28,37,46,50};
        for (i=0;i<4;i++) {
            if (v[i] == a) {
                System.out.println(i);
            }
        }

    }
}
